Acoustic Guitar Construction

See pic. I have to refine the angle to 45* but the board is in place and cannot be moved. Any ideas?? Angle goes the entire 48"
Thanks

Can you post pic of the object?

I could but you've seen it - I'm refining the copy carver.

How about cutting another 2x4 at the correct angle that you want to end up with, then clamp it to the existing 2x4 and using it as a guide as you take a block plane to the first one?

I like it! Thanks Dave.
Any other ideas from you forumites?

I was thinking along the same lines as DD but I'd add a spacer to raise the plane and then use a bottom cutting router bit. The block plane would certainly do the job.

Well, this worked out just fine; as I was rooting around for another 2x4 I spied a 4' length of angled aluminum. So I used my cool tool to scratch a line down the center of the offending 2x4, marked it with a pen. I held a strip of sandpaper inside the aluminum and just made sure the angle bend stayed on the line. Went very quick, the movement of the rollers is much smoother now.
Thanks.